you can switch to the version of the civil 40.10W 4x4 (7170858)* which have 9/47 (1:5,11) this fits without problems in the WM Axle housing.
Here I had written about how to change pinion & crown wheel
threadedit: Other transmission ratios will not fit without changes to the axle housing or pinion/crown wheel , but we have not tested this until now.
* 2200,-€ incl. taxes in 2015.